Shotgun to rifle conversion

I've noticed there are or have been a few single shot break action shotgun/rifle combos out there where you just swap out the barrels like a handi rifle or a savage 219. My question is can I have a rifle barrel made for a single shot break action shotgun that did not come as a combo. Is the break action strong enough for a rifle, but specifically I would like to build one in 44 mag because I think it would be fun to have a little 44mag rifle to compliment my smith 629. I am not considering a 44mag handi rifle because I have heard they are over bored. I'm thinking of using the savage 219 or 220 for a starter.

I've noticed there are or have been a few single shot break action shotgun/rifle combos out there where you just swap out the barrels like a handi rifle or a savage 219. My question is can I have a rifle barrel made for a single shot break action shotgun that did not come as a combo. Is the break action strong enough for a rifle, but specifically I would like to build one in 44 mag because I think it would be fun to have a little 44mag rifle to compliment my smith 629. I am not considering a 44mag handi rifle because I have heard they are over bored. I'm thinking of using the savage 219 or 220 for a starter.

Can it be done, sure, but with some limitations.
Having a custom barrel fit to a break open action you already own is likely to be more expensive than buying another gun.

The 219 savage was made as a break open rifle.
The 220 savage was a bolt action slug gun. Might be hard to convert it to a break open action.

A break open action is strong enough for some cartrages and not for others.
A simple way to decide if a shell would be safe is to consider what the action is currently chambered in.
Use the head diameter and pressures to determine the back thrust of the shell against the standing breach.
Compare those forces to the shell you are considering. A cartrage that generates greater loads than the gun is normaly chambered in should be ignored. Remember, the total force the shell pushes back with is a function of the area of the head and the pressure applied to it, not just the pressure.

Then you have to look and see if the barrel you want to use will fit into the action.

The choice of a rimmed head makes extraction simpler in a break open action.

The fireing pin can be an issue on shotguns firing hand gun shells.
The pin is usualy larger, and protrudes more. This could be a deal breaker if you want to swap back and forth or use a cartrage with a small pistol or small rifle primer.

[QUOTE=Use the head diameter and pressures to determine the back thrust of the shell against the standing breach.
Compare those forces to the shell you are considering. A cartrage that generates greater loads than the gun is normaly chambered in should be ignored. Remember, the total force the shell pushes back with is a function of the area of the head and the pressure applied to it, not just the pressure.
.[/QUOTE]

Ahall, would you be able to post the relevant formula if you have it handy. I assume the pressure is in c.u.p and the force is in ft/lbs ?
It would be a handy one to have on the wall to make the shop look more professional. LOL!

Ahall, would you be able to post the relevant formula if you have it handy. I assume the pressure is in c.u.p and the force is in ft/lbs ?
It would be a handy one to have on the wall to make the shop look more professional. LOL!

I have seen people post the formula for bolt thrust a thousand times JBCGUNS. I have asked a lot of them to explain it or do it in long math or even use it and it usually ends with a lot of erps and harumphs.

The first thing you have to understand is that the case is a vessel and it is also a piston. You can't use the outside of the case or the rim for an exact calculation. You have to use the inside of the vessel at its widest point. If you wanted the exact diameter you can section the case and measure the ID at its widest point. In most cases we just want close numbers for comparison which is just fine so what most people do is just measure the outside of the case at its base. NOT THE RIM.

The formula is normally given as radius squared times Pi times chamber pressure

For an example we can use the 30-06. The outside of the base of the 30-06, or its diameter is .471 inch.

Take the diameter and divide it by 2 to get the radius. Example .471/2=.2355

Now find the square of the area by multiplying the radius by itself
Example .2355*.2355=.05546025

Take that number and multiply it by Pi which is 3.14159
Example .05546025*3.14159=.1742333667975

Multiply that number by your chamber pressure which we will say is 55,000 PSI
Example .1742333667975*55000=9582.83

Which gives us 9,582 foot pounds of bolt thrust. Again this is rough and to high because we are not using the exact widest ID of the case. But its close enough for comparison use. Just going from memory, bolt thrust on most -06 cases is around 6,500 foot pounds if you use the measurement of the widest internal diameter of the case to make your calculation. The math is exactly the same only the starting number changes.

And now you know.

ADD NOTE: There is sort of an old rule of thumb for estimating inside case diameter. Its not exact either but it should give you a closer to reality measurement than using the outside of the base as a lot of people do. In most high intensity metallic cartridges the case wall thickness is roughly .045 inch thick, give or take. If you take .045 inch and double it and then subtract that from the base diameter it gets very close to the inside diameter of the case at the widest point.

Example for our 30-06. .045*2=.090 The 30-06 diameter of .471-.090=.381

If I do the math using .381 inch as my starting diameter instead of .471 inch it works out to 6,270 foot pounds per square inch, which is much closer to the actual bolt thrust.

Thanks for the formula and an example.
So it is the cross-sectional area multiplied by the chamber pressure. Got that. That must also mean that for all practical purposes (ie without accurately measuring case ID at widest point), cartridges with the same case head will produce a bolt thrust directly proportional to chamber pressure.
I show interest in this because I've been asked to keep an eye out for a used military mauser suitable for a particular conversion into a sporter and chamber pressure ratings are may be a concern. (But that would be a story for another thread).

Thanks for the formula and an example.
So it is the cross-sectional area multiplied by the chamber pressure. Got that. That must also mean that for all practical purposes (ie without accurately measuring case ID at widest point), cartridges with the same case head will produce a bolt thrust directly proportional to chamber pressure.
I show interest in this because I've been asked to keep an eye out for a used military mauser suitable for a particular conversion into a sporter and chamber pressure ratings are may be a concern. (But that would be a story for another thread).

For all practical purposes cases of the same head size do indeed give about the same bolt thrusts. There are of course variants. Some brass is thinner or thicker than others and it can make a great deal of difference. Also, some body designs can make a huge amount of differences on brass wall thickness even though the base diameters are the same. 300 H&H and 300 Winchester are markedly different because of their body taper design. The difference between 300 H&H and the old, and I think extinct, 300 H&H flanged is even more radical because the entire case and rim were intended to be supported in the chamber of a double or break action rifle and the web is different. But you have the general idea. Bolt thrust is sort of a relative thing and a novelty measurement, because most actions are rated in PSI of chamber pressure and there are no low pressure belted magnums. About the only time it becomes a factor in day to day work is when people try to rebarrel some of the low pressure Mausers to 45-70 and can't figure out why the actions have set back. It can be done, like it commonly is in the Siamese Mauser and the 45-70 ammo can be had in low pressure rounds, but even with low pressure ammo the huge .505 case base diameter of the 45-70 and its increased bolt thrust can cause problems. It's one of those conversions that's on the ragged edge of working or not working. There are other examples but that is the common one.

The cross sectional area of the shell case should be expressed in square inches and caculated as (3.14 * r * r ) or (3.14*d*d/4).
Useing the OD of the shell at the base provides a good conservitive value.

The pressure should be expressed in PSI (pounds/ sq inch). CUP is roughly equivelant to this, and SAAMI has published pressures for most common cartrages.
The pressure ratings are frequently quoted in reloading manuals and can be found on line.
SAAMI is the authority we usualy go to in North America, although they lack the judicial authority of there european counterpart (CIP).

If you multiply sq inches by pounds per sq inch, your left with pounds, not ft lb or any other unit.
inch lb, ft lb are units of torque.

Many cases with the same head size have different operating pressures. This is more common with rimmed shells that have evolved from black powder rounds into smokelss rounds.
38 S&W is quite different from 357 Mag, but the heads are the same size. Its quite safe to fire 38 S&W or 38 special in a 357, but go the other way and you may have a pile of spare parts.

As cartrages evolved, folks usualy started by modifying existing shells, rather than tooling to make the case. As a result, there are lots of cases based on the same basic case head that very in length, taper and calaber.
577 Snider was modifed to become 577/450, 577 nitro, 577/500 and a few others. If you could put a nitro load in the old snider things would go poorly.
45/70, 45/60, 45/90,45/120, 40/70, 40/82, 33 WFC all share the same head size.
30/30, 32/40, 38/55, 32WFC, 375 Win all share the same head size. 375 win is considerably hotter than the others.
Its stunning how many cases are based on the 8mm mouser (or 30/06). I suspect the abundance of inexpensive actions following WWII made wildcatting economical and some good stuf got adopted.
375 H&H was the parrent for many belted shells

The Savage 219, and 219B were single shot break action rifles, made from 1938 to 1965
The Savage 220, 220A, 220B were single shot break action shotguns made the same time, using the same frame as the sister 219 rifles.
Yes including the small firing pin tip diameter

The Savage 219L was a later version of the rifle, the 220L was a shotgun verison with a larger firing pin tip diameter.

The bad thing about the 219/220/220A actions is that they are are a inline striker fired action, the top lever recocks the striker. That is why they are so hard to open the top lever after they are fired.

The 219B, and 220B, as well as the 219L, and 220L solved this problem by going to a enclosed hammer, that was recocked by a lifter that was operated by the barrel when the barrel was tipped down.

As to rebarreling, yes that can be done, Savage made thousands of 219's in 30-30, which has a operating pressure of aprox 45,000 psi. The 44 mag has the basic same case head and only operates at aprox 36,000 psi.

I currently have a 220A that the shotgun barrel was BAD, so cut it off at 4 inches and set up and made it into a monoblock, and threaded a 44 mag barrel into it. The hard part is you need to pick up a blank or 410 extractor and fit it to the new barrel and chamber. I am just about done with the new stocks for it, so may get some shooting time in yet this fall.

I had hoped to let my son use it but he can not open the action due to the top lever recocking the striker. SO I picked up a NEF versa pak, and will be making some new mono blocks for it and barreling them up for him.

WCFMetalSmith,
Thanks for the reply, that was the kind of info I was looking for. I just wanted to make sure before I started this project that there wasn't something glaringly wrong that I was missing.

OK, next question: How much pressure do you think a 219/220 action can handle? I calculated the 30-30 and 44 mag at 5874 and 5905 pounds, but what about something like a 6.5 grendel at 7061?

The 220A was available in 12 gage.
The pressure is 11500 psi. (Saami speck)
The shell has an inside dia of about .75 inches (Saami OD at mouth =.797 +0/-.020")
Once again we come up with something in the same ball park, about 5080 lb.

Other chamberings for the 219 include 22 hornet,25-20WCF,and 32-20WCF. They have similar head sizes and pressures to the 30-30 and will be in the same ball park for back thrust.

Your considering a shell that increases the load 20% over the hottest rounds found in this action.
I think your pushing your luck.
Its a break open action. Break opens have never been known for having high strengths when compared to other designs.

You may find what you are looking for over at the castboolits@gunbooards.com forums. While some of the conversions featured handi rifles as the basis for the conversion mainly cutting off the origional bbl just in front of the breech section some have oppted to do it a different way. This was done by sleeving the tube (shotgun bbl) affixing with acra glass bedding compound and a few set screws. One of the shotguns converted was a winchester 37. A section of the origional bbl was left and threaded, then the new bbl was also threaded and both were joined by using acra glass. I thing the 37 that was used was in 410 guage. So tere are two ways to convert a small shotgun either by using the bbls as sleeves or by cutting the origional bbl then threarding both the block and breech section of the bbl and coating the threads with acra glass.

Also nitroexpress.com has one of their forums dedicated to building double rifles from selected shotguns. Something you may wish to check out. Frank